Patent Literature 1 discloses an exhaust gas heat exchanging device having a casing in which a heat exchanging core is accommodated. The heat exchanging core is configured to have a plurality of laminated tubes through which an exhaust gas flows. The casing has an inlet port through which a cooling water is introduced in a direction orthogonal to a longitudinal direction, and an outlet port through which the cooling water is discharged in the same orthogonal direction, in the vicinity of both end portions of the tubes in the longitudinal direction. The casing further has an exhaust gas inflow portion and an exhaust gas outflow portion in a tank portion that is positioned on a further outer side than both of the end portions of the plurality of tubes in the longitudinal direction. A core plate holds the plurality of tubes in both of the end portions in the longitudinal direction and partitions a cooling water passage and the tank portion from each other. The core plate is bonded to joint portions that form the tank portion. Accordingly, the core plate is in contact with the cooling water and the joint portions are in contact with the exhaust gas.
According to the above-described configuration, the exhaust gas that flows into the casing from the exhaust gas inflow portion flows through the plurality of tubes therein after passing through an inner portion of the joint portion on one end side. The exhaust gas that flows out from the plurality of tubes passes through an inner portion of the joint portion on the other side, and then is discharged from the exhaust gas outflow portion. When the exhaust gas flows through the plurality of tubes, heat exchange is performed between the exhaust gas and the cooling water that flows through the cooling water passage in the vicinity of the plurality of tubes from the inlet port toward the outlet port. Accordingly, the exhaust gas is cooled by the cooling water only in the heat exchanging core.